JP2005271059A - Joined structure and method for producing joined structure - Google Patents

Joined structure and method for producing joined structure Download PDF

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JP2005271059A
JP2005271059A JP2004090718A JP2004090718A JP2005271059A JP 2005271059 A JP2005271059 A JP 2005271059A JP 2004090718 A JP2004090718 A JP 2004090718A JP 2004090718 A JP2004090718 A JP 2004090718A JP 2005271059 A JP2005271059 A JP 2005271059A
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solder
container
pressure
temperature
joining
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Hideki Okada
秀樹 岡田
Kazunori Nishihara
和則 西原
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Toyota Motor Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/26—Layer connectors, e.g. plate connectors, solder or adhesive layers; Manufacturing methods related thereto
    • H01L2224/31—Structure, shape, material or disposition of the layer connectors after the connecting process
    • H01L2224/32—Structure, shape, material or disposition of the layer connectors after the connecting process of an individual layer connector
    • H01L2224/321—Disposition
    • H01L2224/32151—Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
    • H01L2224/32221—Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
    • H01L2224/32225—Disposition the layer connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being non-metallic, e.g. insulating substrate with or without metallisation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/80—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected
    • H01L2224/83—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected using a layer connector
    • H01L2224/832—Applying energy for connecting
    • H01L2224/8321—Applying energy for connecting using a reflow oven
    • H01L2224/83211—Applying energy for connecting using a reflow oven with a graded temperature profile
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/10—Details of semiconductor or other solid state devices to be connected
    • H01L2924/11—Device type
    • H01L2924/13—Discrete devices, e.g. 3 terminal devices
    • H01L2924/1301—Thyristor
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/10—Details of semiconductor or other solid state devices to be connected
    • H01L2924/11—Device type
    • H01L2924/13—Discrete devices, e.g. 3 terminal devices
    • H01L2924/1304—Transistor
    • H01L2924/1305—Bipolar Junction Transistor [BJT]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/10—Details of semiconductor or other solid state devices to be connected
    • H01L2924/11—Device type
    • H01L2924/13—Discrete devices, e.g. 3 terminal devices
    • H01L2924/1304—Transistor
    • H01L2924/1305—Bipolar Junction Transistor [BJT]
    • H01L2924/13055—Insulated gate bipolar transistor [IGBT]

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Abstract

<P>PROBLEM TO BE SOLVED: To provide a joined structure in which the formation of voids on joining boundaries is reduced, and also, even in case voids are formed on the joining boundaries, the volume of the voids is reduced without depending on the positions at which the voids are formed, and adhesion in the joining boundaries between solder and joining members is excellent, and to provide a method for producing the joined structure. <P>SOLUTION: The one obtained by sandwiching solder 3 between a first joining member 1 and a second joining member 2 is stored in a vessel filled with inert gas. The pressure in the vessel is reduced to a first pressure, and further, the atmospheric temperature is raised to the one higher than the liquidus of the solder, so as to melt the solder. While holding the atmospheric temperature in the vessel to the one higher than the liquidus of the solder, gaseous hydrogen or a gaseous mixture of gaseous hydrogen and inert gas is made to flow into the vessel, and the pressure in the vessel is increased to a second pressure. The atmospheric temperature in the vessel is reduced to the one lower than the solidus of the solder, and the solder is solidified. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

本発明は、第一の接合部材と第二の接合部材とをはんだを介して接合する接合構造体および接合構造体の製造方法に関する。   The present invention relates to a bonded structure for bonding a first bonded member and a second bonded member via solder and a method for manufacturing the bonded structure.

従来、半導体素子等の実装部品からなる第一の接合部材と、絶縁基板からなる第二の接合部材とを、はんだを介して接合する接合構造体の技術は公知となっている。
このような接合構造体を製造する際には、十分な接合強度、優れた熱伝導性（放熱性）および電気伝導性を得るために、（Ａ）第一の接合部材とはんだとの界面、および（Ｂ）はんだと第二の接合部材との界面（以下、（Ａ）、（Ｂ）を合わせて「接合界面」と呼ぶこととする）における高い密着性が要求される。 2. Description of the Related Art Conventionally, a technique for a joined structure that joins a first joining member made of a mounting component such as a semiconductor element and a second joining member made of an insulating substrate via solder is known.
When manufacturing such a bonded structure, in order to obtain sufficient bonding strength, excellent thermal conductivity (heat dissipation) and electrical conductivity, (A) the interface between the first bonding member and the solder, And (B) high adhesion is required at the interface between the solder and the second bonding member (hereinafter, (A) and (B) are collectively referred to as the “bonding interface”).

接合界面における高い密着性を達成するためには、はんだの表面および接合部材の表面に形成された酸化膜を除去し、濡れ性を改善することが重要である。
濡れ性を改善する最も代表的な方法としては、フラックス（一般的にはロジン系やアクリル系の樹脂と、アルコールや芳香族系の溶剤と、活性剤（不要の場合もある）とを混合したもの）を接合部材の表面に塗布する方法が知られている。 In order to achieve high adhesion at the bonding interface, it is important to improve the wettability by removing the oxide film formed on the surface of the solder and the surface of the bonding member.
The most typical method for improving wettability is to mix a flux (generally a rosin or acrylic resin, an alcohol or aromatic solvent, and an activator (sometimes unnecessary). A method is known in which a material is applied to the surface of a joining member.

しかし、スプレーを用いて霧状のフラックスを基板等の接合部材に塗布すると、該霧状のフラックスの一部が基板に取り付けられている半導体素子等の実装部品のはんだとの接合面以外の面に回り込んで付着する。これは、後でワイヤーボンディングを行う際の接合不良の原因となる場合があるため、フラックスを使用せずに接合界面の濡れ性を改善する方法も種々検討されている。   However, when a mist-like flux is applied to a joining member such as a substrate using a spray, a part of the mist-like flux other than the joining surface with the solder of a mounting component such as a semiconductor element attached to the substrate Wrap around and adhere. Since this may cause a bonding failure when wire bonding is performed later, various methods for improving the wettability of the bonding interface without using a flux have been studied.

フラックスを使用せずに接合界面の濡れ性を改善したはんだ付け装置の代表例としては、連続式水素リフロー炉が挙げられる。
これは、水素ガス雰囲気中で、銅やアルミニウム等の金属材料からなる回路パターンが形成された絶縁基板を高温に保持すると、該回路パターンの表面にメッキされたニッケル等の酸化物が雰囲気中の水素と還元反応を起こし、濡れ性が改善される、という性質を利用するものである。 A typical example of a soldering apparatus that improves the wettability of the joint interface without using a flux is a continuous hydrogen reflow furnace.
This is because when an insulating substrate on which a circuit pattern made of a metal material such as copper or aluminum is held at a high temperature in a hydrogen gas atmosphere, an oxide such as nickel plated on the surface of the circuit pattern is present in the atmosphere. It utilizes the property of causing a reduction reaction with hydrogen and improving wettability.

連続式水素リフロー炉の場合、第一の接合部材（例えば半導体素子）と第二の接合部材（例えば絶縁基板）とに挟まれたシート状のはんだが溶融する際に、接合界面においてまだ濡れ性が改善されていない部分（すなわち、ニッケルメッキの酸化物が水素ガスにより十分に還元されてない部分）には溶融したはんだがうまく濡れ広がらず、当該部分にリフロー炉内の雰囲気が残留して溶融したはんだの内部に巻き込まれることにより、接合界面にボイド（気泡）が形成されることがある。
そして、ボイドは接合界面の密着性を低下させる要因であり、第一の接合部材（例えば半導体素子）と第二の接合部材（例えば絶縁基板）との間の接合強度、熱伝導性（放熱性）を低下させる。 In the case of a continuous hydrogen reflow furnace, when the sheet-like solder sandwiched between the first joining member (for example, a semiconductor element) and the second joining member (for example, an insulating substrate) melts, it is still wettable at the joining interface. However, the molten solder does not get wet well and spread in the part where the nickel plating oxide is not sufficiently reduced by hydrogen gas, and the atmosphere in the reflow furnace remains in the part. In some cases, voids (bubbles) are formed at the bonding interface by being caught inside the solder.
The void is a factor that decreases the adhesion at the bonding interface, and the bonding strength between the first bonding member (for example, a semiconductor element) and the second bonding member (for example, an insulating substrate), thermal conductivity (heat dissipation). ).

このような問題を解決する方法として、第一の接合部材（例えば半導体素子）と第二の接合部材（例えば絶縁基板）との間にシート状のはんだを挟んだものを容器に収容し、該容器内を窒素ガス等の不活性ガスで常圧に置換し、容器内の雰囲気温度をはんだが溶融しない範囲で高温に保持しつつ容器内に水素ガスを流入させ、水素ガスによる接合界面の濡れ性の改善を行った後に容器内を所定の圧力まで減圧し、その後更に昇温してはんだの溶融を行い、はんだが溶融した状態を保持しつつ容器内に不活性ガスを導入して常圧に戻し、最後に容器内の圧力をほぼ常圧に保持しつつ温度を下げてはんだを凝固させる方法が知られている。例えば、特許文献１および特許文献２に記載の如くである。
この方法は、接合界面にボイドが形成されるとき（すなわち、はんだが溶融するとき）の容器内の圧力を低く設定し、ボイドに含まれる雰囲気の圧力を低くし、その後容器内の圧力を常圧に戻して（加圧して）ボイドを収縮させることにより、最終的に接合界面に残留するボイドの体積を小さくするものである。 As a method for solving such a problem, a sheet-shaped solder sandwiched between a first bonding member (for example, a semiconductor element) and a second bonding member (for example, an insulating substrate) is accommodated in a container, The inside of the container is replaced with an inert gas such as nitrogen gas at normal pressure, and the atmosphere in the container is kept at a high temperature within a range where the solder does not melt. After improving the performance, the inside of the container is depressurized to a predetermined pressure, and then the temperature is further increased to melt the solder, and an inert gas is introduced into the container while maintaining the state where the solder is melted to normal pressure. Finally, a method is known in which the solder is solidified by lowering the temperature while maintaining the pressure in the container at almost normal pressure. For example, it is as described in Patent Document 1 and Patent Document 2.
In this method, when a void is formed at the joint interface (that is, when the solder is melted), the pressure in the container is set low, the pressure of the atmosphere contained in the void is lowered, and then the pressure in the container is normally maintained. By returning to pressure (pressurizing) and shrinking the void, the volume of the void finally remaining at the bonding interface is reduced.

特開平５−２８３５７０号公報JP-A-5-283570 特開平６−６９３８７号公報JP-A-6-69387

特許文献１および特許文献２に記載のボイド低減方法は、以下の如き問題を有する。
すなわち、図３に示す如く、接合構造体の実施の一形態である実装基板１００において接合界面（半導体素子１の下面および基板２の上面）に形成されたボイド６が、はんだ３および接合界面で完全に囲まれている場合には、ボイド６に含まれる雰囲気と実装基板１００を収容した容器内の雰囲気との間に圧力差を生じさせることが可能である。そのため、該容器内の雰囲気を加圧することにより、ボイドを収縮させることが可能である。
しかし、接合界面に形成されたボイド７がはんだ３および接合界面で完全に囲まれておらず、外部（ここでは容器内の雰囲気）と連通している場合には、実装基板１００を収容した容器内の雰囲気を加圧しても、ボイド７に含まれる雰囲気と容器内の雰囲気との間に圧力差を生じさせることが不可能である。そのため、ボイド７を収縮させることが不可能である。 The void reduction methods described in Patent Document 1 and Patent Document 2 have the following problems.
That is, as shown in FIG. 3, the voids 6 formed on the bonding interface (the lower surface of the semiconductor element 1 and the upper surface of the substrate 2) in the mounting substrate 100, which is an embodiment of the bonding structure, are the solder 3 and the bonding interface. When completely surrounded, it is possible to generate a pressure difference between the atmosphere contained in the void 6 and the atmosphere in the container containing the mounting substrate 100. Therefore, the void can be contracted by pressurizing the atmosphere in the container.
However, when the void 7 formed at the bonding interface is not completely surrounded by the solder 3 and the bonding interface and communicates with the outside (in this case, the atmosphere in the container), the container containing the mounting substrate 100 Even if the inner atmosphere is pressurized, it is impossible to cause a pressure difference between the atmosphere contained in the void 7 and the atmosphere in the container. Therefore, it is impossible to contract the void 7.

本発明は以上の如き状況に鑑み、接合界面におけるボイドの形成自体を低減し、かつ、万一接合界面においてボイドが形成された場合でも、その形成された位置に関わらずボイドの体積を小さくして、はんだと接合部材との接合界面の密着性に優れた接合構造体および接合構造体の製造方法を提供するものである。   In view of the circumstances as described above, the present invention reduces the void formation itself at the bonding interface, and even if a void is formed at the bonding interface, the volume of the void is reduced regardless of the formed position. Thus, the present invention provides a bonded structure excellent in adhesion at the bonded interface between the solder and the bonded member, and a method for manufacturing the bonded structure.

本発明の解決しようとする課題は以上の如くであり、次にこの課題を解決するための手段を説明する。   The problems to be solved by the present invention are as described above. Next, means for solving the problems will be described.

即ち、請求項１においては、第一の接合部材と第二の接合部材とをはんだを介して接合する接合構造体において、
第一の接合部材と第二の接合部材とではんだを挟んだものを不活性ガスで満たした容器に収容し、
該容器内の圧力を第一の圧力まで減圧するとともに雰囲気温度をはんだの液相線以上の温度に上昇させてはんだを溶融し、
該容器内の雰囲気温度をはんだの液相線以上の温度に保持しつつ、容器内に水素ガスまたは水素ガスと不活性ガスとの混合ガスを流入させて該容器内の圧力を第二の圧力まで加圧し、
該容器内の雰囲気温度をはんだの固相線以下の温度に下げてはんだを凝固させたものである。 That is, in the bonded structure for bonding the first bonding member and the second bonding member via solder in claim 1,
Contain the solder sandwiched between the first joining member and the second joining member in a container filled with inert gas,
The pressure in the container is reduced to the first pressure and the ambient temperature is raised to a temperature higher than the liquidus of the solder to melt the solder,
While maintaining the atmospheric temperature in the container at a temperature equal to or higher than the liquidus line of the solder, hydrogen gas or a mixed gas of hydrogen gas and inert gas is allowed to flow into the container to reduce the pressure in the container to the second pressure. Pressurize until
The atmosphere in the container is lowered to a temperature below the solidus of the solder to solidify the solder.

請求項２においては、前記はんだは錫を母材とし、かつ、インジウムおよびビスマスのいずれか一方または両方を添加材として含むものである。   According to a second aspect of the present invention, the solder contains tin as a base material, and contains either or both of indium and bismuth as an additive.

請求項３においては、第一の接合部材と第二の接合部材とをはんだを介して接合する接合構造体の製造方法において、
第一の接合部材と第二の接合部材とではんだを挟んだものを不活性ガスで満たした容器に収容し、
該容器内の圧力を第一の圧力まで減圧するとともに雰囲気温度をはんだの液相線以上の温度に上昇させてはんだを溶融し、
該容器内の雰囲気温度をはんだの液相線以上の温度に保持しつつ、容器内に水素ガスまたは水素ガスと不活性ガスとの混合ガスを流入させて該容器内の圧力を第二の圧力まで加圧し、
該容器内の雰囲気温度をはんだの固相線以下の温度に下げてはんだを凝固させるものである。 In Claim 3, in the manufacturing method of the joined structure which joins the 1st joined member and the 2nd joined member via solder,
Contain the solder sandwiched between the first joining member and the second joining member in a container filled with inert gas,
The pressure in the container is reduced to the first pressure and the ambient temperature is raised to a temperature higher than the liquidus of the solder to melt the solder,
While maintaining the atmospheric temperature in the container at a temperature equal to or higher than the liquidus line of the solder, hydrogen gas or a mixed gas of hydrogen gas and inert gas is allowed to flow into the container to reduce the pressure in the container to the second pressure. Pressurize until
The atmosphere in the container is lowered to a temperature below the solidus of the solder to solidify the solder.

請求項４においては、前記はんだは錫を母材とし、かつ、インジウムおよびビスマスのいずれか一方または両方を添加材として含むものである。   According to a fourth aspect of the present invention, the solder contains tin as a base material and any one or both of indium and bismuth as an additive.

本発明の効果として、以下に示すような効果を奏する。   As effects of the present invention, the following effects can be obtained.

請求項１においては、溶融したはんだと第一の接合部材または第二の接合部材との接合界面に形成されたボイドの位置に関わらず、はんだが凝固する前に該ボイドを収縮または消滅させることができ、接合界面の密着性に優れ、十分な接合強度、優れた熱伝導性（放熱性）および電気伝導性を有する。   In claim 1, regardless of the position of the void formed at the bonding interface between the molten solder and the first bonding member or the second bonding member, the void shrinks or disappears before the solder solidifies. It has excellent adhesion at the bonding interface, has sufficient bonding strength, excellent thermal conductivity (heat dissipation), and electrical conductivity.

請求項２においては、融点が低いはんだを用いた場合でも、接合界面の密着性に優れ、十分な接合強度、優れた熱伝導性（放熱性）および電気伝導性を有する。   In claim 2, even when a solder having a low melting point is used, the adhesiveness at the bonding interface is excellent, and sufficient bonding strength, excellent thermal conductivity (heat dissipation) and electrical conductivity are obtained.

請求項３においては、溶融したはんだと第一の接合部材または第二の接合部材との接合界面に形成されたボイドの位置に関わらず、はんだが凝固する前に該ボイドを収縮または消滅させることができ、接合界面の密着性に優れ、十分な接合強度、優れた熱伝導性（放熱性）および電気伝導性を有する接合構造体を得ることができる。   According to a third aspect of the present invention, the void is contracted or eliminated before the solder solidifies regardless of the position of the void formed at the bonding interface between the molten solder and the first bonding member or the second bonding member. Therefore, it is possible to obtain a bonded structure having excellent adhesion at the bonding interface, sufficient bonding strength, excellent thermal conductivity (heat dissipation), and electrical conductivity.

請求項４においては、融点が低いはんだを用いた場合でも、接合界面の密着性に優れ、十分な接合強度、優れた熱伝導性（放熱性）および電気伝導性を有する接合構造体を得ることができる。   In claim 4, even when a solder having a low melting point is used, a bonded structure having excellent adhesion at the bonding interface, sufficient bonding strength, excellent thermal conductivity (heat dissipation) and electrical conductivity is obtained. Can do.

以下では、図１を用いて本発明に係る接合構造体の実施の一形態である実装基板１００について説明する。
実装基板１００は、半導体素子１と基板２とをはんだ３を介して接合したものである。 Below, the mounting substrate 100 which is one Embodiment of the junction structure which concerns on this invention using FIG. 1 is demonstrated.
The mounting substrate 100 is obtained by joining the semiconductor element 1 and the substrate 2 via the solder 3.

半導体素子１は第一の接合部材の実施の一形態であり、具体例としては、ＩＧＢＴ（Ｉｎｓｕｌａｔｅｄ（またはＩｎｅｒｔｅｄ） Ｇａｔｅ Ｂｉｐｏｌａｒ Ｔｒａｎｓｉｓｔｏｒ）やＧＴＯサイリスタ（Ｇａｔｅ Ｔｕｒｎ Ｏｆｆ Ｔｈｙｒｉｓｔｏｒ）等のパワー半導体が挙げられる。   The semiconductor element 1 is an embodiment of a first bonding member, and specific examples include power semiconductors such as IGBT (Insulated (or Inerted) Gate Bipolar Transistor) and GTO thyristor (Gate Turn Off Thyristor).

基板２は第一の接合部材の実施の一形態であり、絶縁基板２ａと回路パターン２ｂ・２ｃと、を具備する。
絶縁基板２ａは絶縁性材料からなる板状の部材であり、半導体素子１と放熱板５とを絶縁しつつ、半導体素子１にて発生する熱を放熱板５に伝達する（放熱する）ものである。
絶縁基板２ａの具体例としては、紙フェノールやガラスエポキシ等の樹脂系の材料、あるいは、ＡｌＮ等のセラミックスが挙げられる。
回路パターン２ｂ・２ｃは導電性材料からなり、基板２ａの上下の板面（以後、上面および下面と呼ぶ）に形成される。回路パターン２ｂ・２ｃは半導体素子１と他の実装部品等との間の電流経路となるものである。
回路パターン２ｂ・２ｃの具体例としては、銅やアルミニウム、あるいはこれらを母材とする合金等が挙げられる。回路パターン２ｂ・２ｃの表面には耐食性、耐摩耗性、あるいは耐薬品性を向上させるためにニッケル等のメッキが施される。
なお、絶縁基板２ａの下面側に半導体素子１等の実装部品が取り付けられない場合には、回路パターン２ｃを省略することも可能である。 The substrate 2 is an embodiment of the first bonding member, and includes an insulating substrate 2a and circuit patterns 2b and 2c.
The insulating substrate 2a is a plate-like member made of an insulating material, and insulates the semiconductor element 1 and the heat radiating plate 5 while transmitting (dissipating) heat generated in the semiconductor element 1 to the heat radiating plate 5. is there.
Specific examples of the insulating substrate 2a include resin-based materials such as paper phenol and glass epoxy, or ceramics such as AlN.
The circuit patterns 2b and 2c are made of a conductive material, and are formed on upper and lower plate surfaces (hereinafter referred to as an upper surface and a lower surface) of the substrate 2a. The circuit patterns 2b and 2c serve as current paths between the semiconductor element 1 and other mounted components.
Specific examples of the circuit patterns 2b and 2c include copper, aluminum, and alloys based on these. The surface of the circuit patterns 2b and 2c is plated with nickel or the like in order to improve corrosion resistance, wear resistance, or chemical resistance.
In addition, when mounting components, such as the semiconductor element 1, are not attached to the lower surface side of the insulating substrate 2a, the circuit pattern 2c can be omitted.

はんだ３は半導体素子１と基板２（より厳密には、絶縁基板２ａの上面に形成された回路パターン２ｂ）とを接合し、はんだ４は基板２（より厳密には、絶縁基板２ａの下面に形成された回路パターン２ｃ）と放熱板５とを接合する。
はんだ３・４は、錫を母材とし、かつ、鉛、銀、銅、亜鉛、ニッケル、アンチモン、インジウム、ビスマスのうち、いずれか一つまたは二つ以上を添加材として含む合金であれば良い。
なお、「錫を母材とする」とは、錫がはんだの組成に必須であることを示すが、錫の重量比が他の添加材の重量比（の合計）よりも大きいことを要しない。すなわち、錫以外の添加材の合計が５０ｗｔ％を超えても良い。
はんだ３・４の具体例としては、（ａ）一般的な共晶はんだ（錫−鉛合金）の他、（ｂ）高融点の鉛フリーはんだ（錫−銀合金、錫−銀−銅合金）、（ｃ）低融点の鉛フリーはんだ（錫−インジウム合金、錫−ビスマス合金、錫−インジウム−ビスマス合金）等が挙げられる。 The solder 3 joins the semiconductor element 1 and the substrate 2 (more precisely, the circuit pattern 2b formed on the upper surface of the insulating substrate 2a), and the solder 4 adheres to the substrate 2 (more precisely, the lower surface of the insulating substrate 2a). The formed circuit pattern 2c) and the heat sink 5 are joined.
The solder 3 or 4 may be an alloy containing tin as a base material and any one or more of lead, silver, copper, zinc, nickel, antimony, indium, and bismuth as an additive. .
“Tin is used as a base material” means that tin is essential for the composition of the solder, but it is not necessary that the weight ratio of tin is larger than the total weight ratio of other additives. . That is, the total of additives other than tin may exceed 50 wt%.
Specific examples of the solders 3 and 4 include (a) general eutectic solder (tin-lead alloy) and (b) high melting point lead-free solder (tin-silver alloy, tin-silver-copper alloy). (C) low melting point lead-free solder (tin-indium alloy, tin-bismuth alloy, tin-indium-bismuth alloy), and the like.

放熱板５は半導体素子１にて発生した熱を実装基板１００の外部に放熱するものであり、銅または銅−モリブデン合金等、熱伝導性に優れた材料で構成される。
なお、本実施例は基板２と放熱板５とをはんだ４を介して接合することから、放熱板５を第一の接合部材、基板２を第二の接合部材とする接合構造体を兼ねる。 The heat radiating plate 5 radiates heat generated in the semiconductor element 1 to the outside of the mounting substrate 100 and is made of a material having excellent thermal conductivity such as copper or copper-molybdenum alloy.
In addition, since the present Example joins the board | substrate 2 and the heat sink 5 via the solder 4, it serves also as the joining structure which uses the heat sink 5 as a 1st joining member and the board | substrate 2 as a 2nd joining member.

以下では、図２、図３および図４を用いて実装基板１００の製造方法の一例について説明する。なお、本実施例では、はんだ３・４として錫−銀−銅合金からなる鉛フリーはんだを用いているが、本発明に係る接合構造体の製造方法は、温度、圧力および時間等の条件を適宜選択することにより、あらゆるはんだに対して適用可能である。
図２に示す如く、本実施例における実装基板１００の製造方法は、（１）の時間帯に対応する「初期セット工程」、（２）の時間帯に対応する「減圧工程」、（３）の時間帯に対応する「不活性ガス置換工程」、（４）の時間帯に対応する「水素流入工程」、（５）の時間帯に対応する「減圧下はんだ溶融工程」、（６）の時間帯に対応する「水素ガス加圧工程」、（７）の時間帯に対応する「はんだ凝固工程」、（８）の時間帯に対応する「接合構造体取り出し工程」を順に行うものである。
「初期セット工程」において、半導体素子１と基板２とでシート状のはんだ３を挟み、さらに該基板２と放熱板５とでシート状のはんだ４を挟んだもの、を容器（図示せず）に収容する。「初期セット工程」が終了したら、「減圧工程」に移行する。 Below, an example of the manufacturing method of the mounting substrate 100 is demonstrated using FIG.2, FIG.3 and FIG.4. In this embodiment, lead-free solder made of a tin-silver-copper alloy is used as the solders 3 and 4. However, the method for manufacturing a joined structure according to the present invention requires conditions such as temperature, pressure, and time. Appropriate selection is applicable to any solder.
As shown in FIG. 2, the manufacturing method of the mounting substrate 100 in this embodiment includes an “initial setting step” corresponding to the time zone (1), a “decompression step” corresponding to the time zone (2), and (3). “Inert gas replacement process” corresponding to the time zone of “4”, “hydrogen inflow process” corresponding to the time zone of (4), “solder melting process under reduced pressure” corresponding to the time zone of (5), The “hydrogen gas pressurizing step” corresponding to the time zone, the “solder solidification step” corresponding to the time zone of (7), and the “joined structure taking-out step” corresponding to the time zone of (8) are sequentially performed. .
In the “initial setting step”, a sheet-shaped solder 3 is sandwiched between the semiconductor element 1 and the substrate 2 and a sheet-shaped solder 4 is sandwiched between the substrate 2 and the heat radiating plate 5 as a container (not shown). To house. When the “initial setting process” is completed, the process proceeds to the “decompression process”.

「減圧工程」において、半導体素子１と基板２とでシート状のはんだ３を挟み、さらに該基板２と放熱板５とでシート状のはんだ４を挟んだものを収容した容器内を真空引きして減圧する。本実施例の場合は、容器内の圧力を１．０×１０＾１［Ｐａ］程度まで減圧する。なお、本明細書中においては「Ｎ＾Ｍ」は「ＮのＭ乗」を表すものとする。
また、「減圧工程」における圧力は本実施例に限定されず、初期セット工程における容器内圧力より低ければ効果を奏する。
「減圧工程」が終了したら、「不活性ガス置換工程」に移行する。 In the “decompression step”, the inside of the container containing the sheet-like solder 3 sandwiched between the semiconductor element 1 and the substrate 2 and the sheet-like solder 4 sandwiched between the substrate 2 and the heat sink 5 is evacuated. And depressurize. In the case of the present embodiment, the pressure in the container is reduced to about 1.0 × 10 ^ 1 [Pa]. In this specification, “N ^ M” represents “N to the power of M”.
Further, the pressure in the “depressurization step” is not limited to this example, and an effect is obtained if it is lower than the pressure in the container in the initial setting step.
When the “decompression step” is completed, the process proceeds to the “inert gas replacement step”.

「不活性ガス置換工程」において、不活性ガスを容器内に導入して、容器内の圧力を常圧（１．０×１０＾５［Ｐａ］程度）まで戻し、容器内の雰囲気を空気から不活性ガスに置換する。
なお、本明細書中における「不活性ガス」とは、アルゴンガス等の希ガスまたは窒素ガス、またはこれらを混合したものを含むものとする。
また、本実施例においては、「不活性ガス置換工程」において常圧に戻したが、不活性ガスを導入することにより、容器内の圧力を前記減圧工程における容器内圧力よりも高くすれば良く、不活性ガス置換工程終了時の容器内圧力は常圧に限定されない。
「不活性ガス置換工程」が終了したら、「水素流入工程」に移行する。 In the “inert gas replacement step”, an inert gas is introduced into the container, the pressure in the container is returned to normal pressure (about 1.0 × 10 ^ 5 [Pa]), and the atmosphere in the container is changed from air. Replace with inert gas.
The “inert gas” in this specification includes a rare gas such as an argon gas, a nitrogen gas, or a mixture thereof.
Further, in this example, the pressure was returned to normal pressure in the “inert gas replacement step”, but by introducing the inert gas, the pressure in the vessel may be made higher than the pressure in the vessel in the pressure reducing step. The pressure in the container at the end of the inert gas replacement step is not limited to normal pressure.
When the “inert gas replacement step” is completed, the process proceeds to the “hydrogen inflow step”.

「水素流入工程」において、容器内の圧力を常圧程度に保持しつつ容器内の雰囲気温度を上昇させ、該温度をはんだ３・４が溶融しない温度（固相線以下の温度）の範囲内で極力高くなるように保持する（本実施例の場合は、２００℃から２５０℃程度に保持する）とともに、容器内に水素ガスまたは水素ガスと前記不活性ガスとの混合ガスを流入させる。   In the “hydrogen inflow process”, the atmospheric temperature in the container is raised while maintaining the pressure in the container at about normal pressure, and the temperature is within the range where the solder 3 and 4 do not melt (temperature below the solidus). (In the case of this embodiment, the temperature is maintained at about 200 ° C. to 250 ° C.), and hydrogen gas or a mixed gas of hydrogen gas and the inert gas is allowed to flow into the container.

このとき、雰囲気中の水素ガスと、回路パターン２ｂ・２ｃ表面のニッケルメッキの酸化物（ＮｉＯやＮｉＯ２等）とが還元反応して、ニッケルメッキ表面の濡れ性が改善される。
なお、雰囲気温度をはんだ３・４が溶融しない温度（固相線以下の温度）の範囲内で極力高くなるように保持するのは、ニッケルメッキ表面の濡れ性が改善される前にはんだが溶融し始めるのを防止しつつ、水素ガスによる還元反応を促進するためである。
また、「水素流入工程」における容器内の圧力は常圧に限定されないが、容器に排出口を設け、水素ガスを容器内に流入させつつ該排出口から容器内のガスを排出し、容器内の圧力を常圧よりもやや高い圧力に保持するのが実施容易である。
「水素流入工程」が終了したら、「減圧下はんだ溶融工程」に移行する。 At this time, the hydrogen gas in the atmosphere and the nickel plating oxide (NiO, NiO2, etc.) on the surface of the circuit patterns 2b and 2c undergo a reduction reaction, and the wettability of the nickel plating surface is improved.
Note that the ambient temperature is kept as high as possible within the temperature range where the solder 3 and 4 do not melt (the temperature below the solidus), so that the solder melts before the wettability of the nickel plating surface is improved. This is to promote the reduction reaction by hydrogen gas while preventing the start of the starting.
Further, the pressure in the container in the “hydrogen inflow process” is not limited to normal pressure, but the container is provided with a discharge port, and the gas in the container is discharged from the discharge port while flowing hydrogen gas into the container. It is easy to carry out maintaining the pressure at a pressure slightly higher than the normal pressure.
When the “hydrogen inflow process” is completed, the process proceeds to a “solder melting process under reduced pressure”.

「減圧下はんだ溶融工程」において、容器内への水素ガスまたは水素ガスと前記不活性ガスとの混合ガスの流入を停止し、容器内を真空引きして減圧する。本実施例の場合は、容器内の圧力を１．０×１０＾１［Ｐａ］程度まで減圧する。
そして、容器内の雰囲気温度を半導体素子１の耐熱温度以下、かつ、はんだ３・４が溶融する温度（液相線以上の温度）以上となる温度に保持し、はんだ３・４を溶融させる（本実施例の場合は、２５０℃から３００℃程度に保持する）。
このとき、回路パターン２ｂ・２ｃ表面には、水素ガスとニッケルメッキの酸化物（ＮｉＯやＮｉＯ２等）との間の還元反応が十分に行われておらず、濡れ性が改善されていない部分が残っている場合がある。そして、濡れ性が改善されていない部分には、図３に示す如く、溶融したはんだ３・４が濡れ広がらないために、溶融したはんだ３・４が雰囲気ガスを巻き込んでボイド（ボイド６・ボイド７・ボイド８・ボイド９等）を形成する場合がある。
なお、「減圧下はんだ溶融工程」における容器内の圧力（第一の圧力）は、本実施例の圧力（１．０×１０＾１［Ｐａ］）には限定されないが、ボイドの体積を小さくするという観点から見て、後述する「水素ガス加圧工程」の終了時の容器内圧力（第二の圧力）との差が大きくなるように構成することが望ましい。
「減圧下はんだ溶融工程」が終了したら、「水素ガス加圧工程」に移行する。 In the “solder melting step under reduced pressure”, the flow of hydrogen gas or a mixed gas of hydrogen gas and the inert gas into the container is stopped, and the inside of the container is evacuated to reduce the pressure. In the case of the present embodiment, the pressure in the container is reduced to about 1.0 × 10 ^ 1 [Pa].
Then, the ambient temperature in the container is maintained at a temperature equal to or lower than the heat resistant temperature of the semiconductor element 1 and equal to or higher than a temperature at which the solder 3 or 4 is melted (temperature above the liquidus), and the solder 3 or 4 is melted ( In the case of this example, the temperature is maintained at about 250 ° C. to 300 ° C.).
At this time, on the surface of the circuit patterns 2b and 2c, there is a portion where the reduction reaction between hydrogen gas and nickel plating oxide (NiO, NiO2, etc.) is not sufficiently performed and the wettability is not improved. It may remain. As shown in FIG. 3, the melted solder 3 and 4 do not wet and spread in the portion where the wettability is not improved. 7 / void 8 / void 9) may be formed.
The pressure in the container (first pressure) in the “reduced solder melting step” is not limited to the pressure (1.0 × 10 ^ 1 [Pa]) of this embodiment, but the void volume is reduced. In view of the above, it is desirable to configure so that the difference from the internal pressure (second pressure) at the end of the “hydrogen gas pressurizing step” described later becomes large.
When the “reduced solder melting step” is completed, the process proceeds to the “hydrogen gas pressurizing step”.

「水素ガス加圧工程」において、容器内の雰囲気温度を半導体素子１の耐熱温度以下、かつ、はんだ３・４が溶融する温度（液相線以上の温度）以上となる温度（本実施例の場合は、２５０℃から３００℃程度）に保持しつつ、容器内に水素ガスまたは水素ガスと不活性ガスとの混合ガスを流入させて常圧に戻す。   In the “hydrogen gas pressurizing step”, the temperature of the atmosphere in the container is equal to or lower than the heat resistance temperature of the semiconductor element 1 and equal to or higher than the temperature at which the solder 3 and 4 melt (temperature above the liquidus). In this case, hydrogen gas or a mixed gas of hydrogen gas and an inert gas is allowed to flow into the container to return to normal pressure while maintaining the temperature at about 250 ° C. to 300 ° C.).

このとき、図４に示す如く、はんだ３と半導体１と基板２とに完全に囲まれて外部と連通していないボイド６、および、はんだ４と基板２と放熱板５とに完全に囲まれて外部と連通していないボイド８は、その内部に含まれる雰囲気の圧力が減圧時の圧力であるため、容器内の圧力の上昇とともに収縮する。   At this time, as shown in FIG. 4, the solder 6, the semiconductor 1 and the substrate 2 are completely surrounded by the void 6 which is not in communication with the outside, and the solder 4, the substrate 2 and the heat sink 5 are completely surrounded. The void 8 that is not in communication with the outside contracts as the pressure in the container increases because the pressure of the atmosphere contained therein is the pressure at the time of decompression.

一方、ボイド７およびボイド９は、はんだと接合部材とで完全に囲まれておらず、外部（容器内の雰囲気）と連通しているため、ボイド７およびボイド９に含まれる雰囲気の圧力は容器内の雰囲気の圧力上昇とともに上昇する。従って、ボイド７およびボイド９に含まれる雰囲気と容器内の雰囲気との圧力差によりボイド７およびボイド９が収縮することはない。
しかし、容器内の圧力を常圧に戻す（上昇させる）ために容器内に流入するガスは、水素ガスまたは水素ガスと不活性ガスとの混合ガスである。そのため、水素ガスがボイド７およびボイド９により生じる空間（言い換えれば、水素流入工程において水素による還元反応が十分に行われていない部分）に供給される。
しかも、「水素ガス加圧工程」における雰囲気温度は、はんだ３・４の液相線以上の温度であり、「水素流入工程」における雰囲気温度（はんだ３・４の固相線以下の温度）よりも高く設定されている。そのため、回路パターン２ｂ・２ｃ表面においてボイド７およびボイド９の発生原因となっていた部分の還元反応がより促進され、濡れ性が改善される。
従って、はんだ３・４は、「水素ガス加圧工程」において新たに濡れ性が改善された部分に沿って濡れ広がるので、ボイド７およびボイド９は縮小し、ひいては消滅する。 On the other hand, since the void 7 and the void 9 are not completely surrounded by the solder and the joining member and communicate with the outside (the atmosphere in the container), the pressure of the atmosphere contained in the void 7 and the void 9 is the container. It rises with increasing pressure in the atmosphere. Therefore, the void 7 and the void 9 are not contracted by the pressure difference between the atmosphere contained in the void 7 and the void 9 and the atmosphere in the container.
However, the gas flowing into the container in order to return (increase) the pressure in the container to normal pressure is hydrogen gas or a mixed gas of hydrogen gas and inert gas. Therefore, hydrogen gas is supplied to the space formed by the void 7 and the void 9 (in other words, the portion where the reduction reaction by hydrogen is not sufficiently performed in the hydrogen inflow step).
Moreover, the atmospheric temperature in the “hydrogen gas pressurizing step” is a temperature higher than the liquidus line of the solder 3 and 4, and the atmospheric temperature in the “hydrogen inflow step” (the temperature below the solidus line of the solder 3 and 4). Is also set high. For this reason, the reduction reaction of the portion that has caused the void 7 and the void 9 on the surface of the circuit patterns 2b and 2c is further promoted, and the wettability is improved.
Therefore, since the solder 3 and 4 are wet and spread along the portion where the wettability is newly improved in the “hydrogen gas pressurizing step”, the voids 7 and 9 are reduced and eventually disappear.

このように、「水素ガス加圧工程」において、溶融したはんだと接合部材との接合界面に形成されたボイドは、該ボイドの形成位置に関わらず（外部と連通しているか否かに関わらず）収縮または消滅する。
なお、本実施例では「水素ガス加圧工程」終了時の容器内の圧力（第二の圧力）は常圧としたが、これには限定されず、前記「減圧下はんだ溶融工程」における容器内の圧力（第一の圧力）より高い圧力であれば同様の効果を奏する。
「水素ガス加圧工程」が終了したら、「はんだ凝固工程」に移行する。 As described above, in the “hydrogen gas pressurizing step”, the void formed at the bonding interface between the molten solder and the bonding member is irrespective of the formation position of the void (whether or not it communicates with the outside). ) Shrink or disappear.
In this embodiment, the pressure in the container at the end of the “hydrogen gas pressurizing step” (second pressure) is normal pressure, but is not limited to this, and the container in the “solder melting step under reduced pressure” is used. If the pressure is higher than the internal pressure (first pressure), the same effect is obtained.
When the “hydrogen gas pressurization process” is completed, the process proceeds to the “solder solidification process”.

「はんだ凝固工程」において、容器内の圧力を常圧に保持しつつ、容器内の雰囲気温度をはんだ３・４の固相線以下の温度に下げ、さらに常温（２５℃）付近まで下げる。
このようにして、接合界面のボイドが収縮または消滅した状態ではんだ３・４を凝固させ、実装基板１００（より厳密には、実装基板１００にはんだ４を介して放熱板５を接合したもの）を得る。
「はんだ凝固工程」が終了したら、「接合構造体取り出し工程」に移行する。 In the “solder solidification step”, while maintaining the pressure in the container at normal pressure, the atmospheric temperature in the container is lowered to a temperature below the solidus of the solder 3 and 4 and further lowered to around room temperature (25 ° C.).
In this way, the solders 3 and 4 are solidified in a state where the voids at the bonding interface contract or disappear, and the mounting substrate 100 (strictly, the heat sink 5 is bonded to the mounting substrate 100 via the solder 4). Get.
When the “solder solidification process” is completed, the process proceeds to the “joined structure take-out process”.

「接合構造体取り出し工程」において、容器から実装基板１００を取り出す。   In the “joined structure taking-out step”, the mounting substrate 100 is taken out from the container.

以上の如く、本発明に係る接合構造体の実施の一形態である実装基板１００は、
第一の接合部材である半導体素子１と第二の接合部材である基板２とをはんだ３を介して接合するものであり、
半導体素子１と基板２とではんだ３を挟んだものを窒素ガスからなる不活性ガスで満たした容器に収容し、
該容器内の圧力を第一の圧力（本実施例の場合、１．０×１０＾１［Ｐａ］）まで減圧するとともに雰囲気温度をはんだ３の液相線以上の温度（本実施例の場合、２５０℃から３００℃程度）に上昇させてはんだ３を溶融し、
該容器内の雰囲気温度をはんだ３の液相線以上の温度に保持しつつ、容器内に水素ガスまたは水素ガスと不活性ガスとの混合ガスを流入させて該容器内の圧力を第二の圧力（本実施例の場合、１．０×１０＾５［Ｐａ］程度の常圧）まで加圧し、
該容器内の雰囲気温度をはんだ３の固相線以下の温度に下げてはんだ３を凝固させた、ものである。 As described above, the mounting substrate 100 which is an embodiment of the bonded structure according to the present invention is
The semiconductor element 1 as the first bonding member and the substrate 2 as the second bonding member are bonded via the solder 3,
The semiconductor element 1 and the substrate 2 sandwiched between the solder 3 are housed in a container filled with an inert gas made of nitrogen gas,
The pressure in the container is reduced to the first pressure (1.0 × 10 ^ 1 [Pa] in the case of this embodiment) and the ambient temperature is a temperature higher than the liquidus of the solder 3 (in the case of this embodiment). , From 250 ° C. to about 300 ° C.) to melt the solder 3,
While maintaining the atmospheric temperature in the container at a temperature equal to or higher than the liquidus line of the solder 3, hydrogen gas or a mixed gas of hydrogen gas and inert gas is allowed to flow into the container to reduce the pressure in the container to the second pressure. Pressurize to a pressure (in the case of the present embodiment, a normal pressure of about 1.0 × 10 ^ 5 [Pa]),
The atmosphere in the container is lowered to a temperature below the solidus of the solder 3 to solidify the solder 3.

このように構成することにより、溶融したはんだ３と半導体素子１または基板２との接合界面に形成されたボイド６・７は、該ボイド６・７が形成された位置に関わらず（外部と連通しているか否かに関わらず）、該ボイド６・７ははんだ３が凝固する前に収縮または消滅する。
従って、実装基板１００は接合界面の密着性に優れ、十分な接合強度、優れた熱伝導性（放熱性）および電気伝導性を得ることができる。 With this configuration, the voids 6 and 7 formed at the bonding interface between the molten solder 3 and the semiconductor element 1 or the substrate 2 are communicated with the outside regardless of the positions where the voids 6 and 7 are formed. The voids 6 and 7 contract or disappear before the solder 3 solidifies.
Therefore, the mounting substrate 100 has excellent adhesion at the bonding interface, and can obtain sufficient bonding strength, excellent thermal conductivity (heat dissipation) and electrical conductivity.

特に、接合構造体がパワー半導体装置（ＩＧＢＴモジュール等）のように発熱量が大きいものの場合、半導体素子の構成材料であるシリコンの線膨張係数は３ｐｐｍ／℃程度、絶縁基板の一例であるＡｌＮの線膨張係数は４．５〜４．６ｐｐｍ／℃程度、放熱板の一例である銅の線膨張係数は１７ｐｐｍ／℃程度であることから、放熱板と絶縁基板との間の線膨張係数の差が大きく、これらを接合するはんだの凝固温度が高いと、凝固温度と常温との温度差が大きく、接合構造体に残留する応力（歪み）が大きくなる。これは、熱サイクルによる接合不良の原因となる可能性がある。
そこで、近年、第一の接合部材および第二の接合部材の線膨張係数の差に起因して接合構造体に残留する応力（歪み）を、第一の接合部材と第二の接合部材とを接合するはんだの凝固温度を低くすることにより軽減することが検討されている。
このような場合に使用されるはんだとしては、錫−インジウム合金、錫−ビスマス合金、錫−インジウム−ビスマス合金、あるいは錫に鉛、銀、銅、亜鉛、ニッケル、アンチモン等を添加した合金である。
より具体的には、インジウムを２ｗｔ％から２０ｗｔ％添加した錫−インジウム合金、インジウムとビスマスとを合わせて２ｗｔ％から２０ｗｔ％添加した錫−インジウム−ビスマス合金、ビスマスを３ｗｔ％から５８ｗｔ％添加した錫−ビスマス合金等が低融点のはんだの例として挙げられる。
しかし、はんだの融点が低くなると、前記「水素流入工程」において水素ガスによる還元反応を行う温度も低くなる。そのため、「水素流入工程」において還元反応が十分に促進されず、接合界面において濡れ性が改善されない部分が多く残り、「減圧下はんだ溶融工程」において接合界面にボイドが多数発生するという問題がある。 In particular, when the bonding structure has a large calorific value such as a power semiconductor device (IGBT module or the like), the linear expansion coefficient of silicon, which is a constituent material of the semiconductor element, is about 3 ppm / ° C., and AlN, which is an example of an insulating substrate, is used. Since the linear expansion coefficient is about 4.5 to 4.6 ppm / ° C., and the linear expansion coefficient of copper, which is an example of the heat sink, is about 17 ppm / ° C., the difference in the linear expansion coefficient between the heat sink and the insulating substrate When the solidification temperature of the solder that joins them is high, the temperature difference between the solidification temperature and normal temperature is large, and the stress (strain) remaining in the joint structure increases. This can cause poor bonding due to thermal cycling.
Therefore, in recent years, the stress (strain) remaining in the bonded structure due to the difference in the coefficient of linear expansion between the first bonding member and the second bonding member is obtained by using the first bonding member and the second bonding member. It has been studied to reduce the solidification temperature of the solder to be joined by lowering it.
The solder used in such a case is a tin-indium alloy, a tin-bismuth alloy, a tin-indium-bismuth alloy, or an alloy obtained by adding lead, silver, copper, zinc, nickel, antimony, or the like to tin. .
More specifically, a tin-indium alloy with indium added at 2 wt% to 20 wt%, a tin-indium-bismuth alloy with indium and bismuth added at 2 wt% to 20 wt%, and bismuth added at 3 wt% to 58 wt%. A tin-bismuth alloy or the like is an example of a low melting point solder.
However, when the melting point of the solder is lowered, the temperature at which the reduction reaction with hydrogen gas is performed in the “hydrogen inflow process” is also lowered. Therefore, the reduction reaction is not sufficiently promoted in the “hydrogen inflow process”, and there are many portions where the wettability is not improved at the joint interface, and a large number of voids are generated at the joint interface in the “solder melting process under reduced pressure”. .

本発明に係る接合構造体の製造方法は、このような低融点のはんだを用いて接合構造体を製造する場合にも、「水素ガス加圧工程」においてはんだが溶融している温度（液相線以上）にて水素ガスによる還元反応を行うため、接合界面の濡れ性が改善され、良好な密着性を有する接合界面を形成することが可能である。   The method for manufacturing a bonded structure according to the present invention also includes a temperature (liquid phase) at which the solder is melted in the “hydrogen gas pressurizing step” even when a bonded structure is manufactured using such a low melting point solder. Since the reduction reaction with hydrogen gas is performed at a line or higher), the wettability of the bonding interface is improved, and it is possible to form a bonding interface having good adhesion.

本発明に係る接合構造体の実施の一形態である実装基板を示す側面模式図。The side surface schematic diagram which shows the mounting substrate which is one Embodiment of the junction structure which concerns on this invention. 本発明に係る接合構造体の製造方法の一実施例の温度および圧力のパターンを示す図。The figure which shows the pattern of the temperature and pressure of one Example of the manufacturing method of the junction structure which concerns on this invention. 接合構造体の接合界面にボイドが発生した状態を示す側面断面模式図。The side surface cross-section schematic diagram which shows the state which the void generate | occur | produced in the joining interface of the joining structure. 接合構造体の接合界面に発生したボイドを収縮および消滅させた状態を示す側面断面模式図。The side surface cross-sectional schematic diagram which shows the state which the void which generate | occur | produced in the joining interface of the joining structure was shrunk and eliminated.

符号の説明Explanation of symbols

１ 半導体素子（第一の接合部材）
２ 基板（第二の接合部材）
３ はんだ 1 Semiconductor element (first bonding member)
2 Substrate (second bonding member)
3 Solder

Claims (4)

第一の接合部材と第二の接合部材とをはんだを介して接合する接合構造体において、
第一の接合部材と第二の接合部材とではんだを挟んだものを不活性ガスで満たした容器に収容し、
該容器内の圧力を第一の圧力まで減圧するとともに雰囲気温度をはんだの液相線以上の温度に上昇させてはんだを溶融し、
該容器内の雰囲気温度をはんだの液相線以上の温度に保持しつつ、容器内に水素ガスまたは水素ガスと不活性ガスとの混合ガスを流入させて該容器内の圧力を第二の圧力まで加圧し、
該容器内の雰囲気温度をはんだの固相線以下の温度に下げてはんだを凝固させた、
ことを特徴とする接合構造体。 In the joined structure that joins the first joining member and the second joining member via solder,
Contain the solder sandwiched between the first joining member and the second joining member in a container filled with inert gas,
The pressure in the container is reduced to the first pressure and the ambient temperature is raised to a temperature higher than the liquidus of the solder to melt the solder,
While maintaining the atmospheric temperature in the container at a temperature equal to or higher than the liquidus line of the solder, hydrogen gas or a mixed gas of hydrogen gas and inert gas is allowed to flow into the container to reduce the pressure in the container to the second pressure. Pressurize until
Lowering the ambient temperature in the container to a temperature below the solidus of the solder to solidify the solder;
A bonded structure characterized by that. 前記はんだは錫を母材とし、かつ、インジウムおよびビスマスのいずれか一方または両方を添加材として含むことを特徴とする請求項１に記載の接合構造体。   The joint structure according to claim 1, wherein the solder includes tin as a base material and one or both of indium and bismuth as an additive. 第一の接合部材と第二の接合部材とをはんだを介して接合する接合構造体の製造方法において、
第一の接合部材と第二の接合部材とではんだを挟んだものを不活性ガスで満たした容器に収容し、
該容器内の圧力を第一の圧力まで減圧するとともに雰囲気温度をはんだの液相線以上の温度に上昇させてはんだを溶融し、
該容器内の雰囲気温度をはんだの液相線以上の温度に保持しつつ、容器内に水素ガスまたは水素ガスと不活性ガスとの混合ガスを流入させて該容器内の圧力を第二の圧力まで加圧し、
該容器内の雰囲気温度をはんだの固相線以下の温度に下げてはんだを凝固させる、
ことを特徴とする接合構造体の製造方法。 In the manufacturing method of the bonded structure in which the first bonding member and the second bonding member are bonded via solder,
Contain the solder sandwiched between the first joining member and the second joining member in a container filled with inert gas,
The pressure in the container is reduced to the first pressure and the ambient temperature is raised to a temperature higher than the liquidus of the solder to melt the solder,
While maintaining the atmospheric temperature in the container at a temperature equal to or higher than the liquidus line of the solder, hydrogen gas or a mixed gas of hydrogen gas and inert gas is allowed to flow into the container to reduce the pressure in the container to the second pressure. Pressurize until
Lowering the ambient temperature in the container to a temperature below the solidus of the solder to solidify the solder;
The manufacturing method of the joining structure characterized by the above-mentioned. 前記はんだは錫を母材とし、かつ、インジウムおよびビスマスのいずれか一方または両方を添加材として含むことを特徴とする請求項３に記載の接合構造体の製造方法。   4. The method for manufacturing a joint structure according to claim 3, wherein the solder includes tin as a base material and one or both of indium and bismuth as an additive.
JP2004090718A 2004-03-26 2004-03-26 Joined structure and method for producing joined structure Pending JP2005271059A (en)

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